On August 27, 2026, VolRoc recorded 224,816 active prediction markets across Kalshi and Polymarket, holding $1.77B in combined open interest. Day over day, active markets fell 4.0% and open interest was little changed (vs August 26, 2026). Politics & Elections was the largest domain by open interest (32%), ahead of Sports (21%); together they accounted for 54% of all open interest. Kalshi carried 74% of active markets and Polymarket 26%.
Deterministic · template v1 · 2026-08-27
As of 2026-08-27 · 00:00 UTC
Active Markets
224,816
00:00 UTC freeze
Open Interest
$1.77B
Kalshi OI + Polymarket liquidity
Markets Traded · 24h
24,742
with trading activity
Kalshi / Polymarket
74% / 26%
by active-market count
Domain Composition — 12 domains
Mixed / Multi-category
127,550
Other
38,875
Sports
35,957
Politics & Elections
10,419
Entertainment & Culture
3,304
Crypto & Digital Assets
1,960
Technology & AI
1,773
Climate & Weather
1,366
Companies & Business
1,030
Economics & Inflation
1,009
World & Geopolitics
926
Monetary Policy
519
Science & Health
128
Venue-agnostic subject taxonomy from Kalshi series prefixes and
Polymarket title keywords. A residual Other bucket is reported honestly.
Yes-price across both venues, 10 buckets from 0 to 100. n = 224,816.
Largest Kalshi Series
Cross-category multi-markets
127,550
—
4,094
Midterm control
1,194
Music — artist streams
756
U.S. House races
614
Nextteamnba
509
Nflspread
453
Nflwins
358
Ncaafgame
342
Ncaafwins
319
Primary vote shares
309
Mlbhrr
294
Kalshi market families (Polymarket is not series-structured).
About & Citation
This is the fixed-hour (00:00 UTC) state of every active market on
Kalshi and Polymarket for August 27, 2026. The live
Observatory
shows the current diurnal value; this record is immutable. Open interest combines Kalshi
open interest with Polymarket USD liquidity as comparable USD magnitudes. Sources: Kalshi, Polymarket.
How to cite
“VolRoc Prediction Market Archive — August 27, 2026.” https://volroc.ai/prediction-markets/2026-08-27/
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